RESUMEN
Background: A wide range of diseases, such as systemic sclerosis, can be diagnosed by imaging the nailfold microcirculation, which is conventionally performed using capillaroscopy. This study applied optical coherence tomography angiography (OCTA) as a novel high resolution imaging method for the qualitative and quantitative assessment of the nailfold microvasculature, and compared OCTA imaging with capillaroscopy. Methods: For qualitative assessment, high resolution OCTA imaging was used to achieve images that contained a wide field of view of the nailfold microvasculature through mosaic scanning. OCTA imaging was also used to observe the characteristic changes in the microvasculature under external compression of the upper arm. For quantitative evaluation, the capillary density and the capillary diameter of the nailfold microvasculature were assessed with both OCTA and capillaroscopy by repeated measurements over 2 days in 13 normal subjects. The results were analyzed using the intraclass correlation coefficient (ICC). Results: OCTA imaging showed the typical nailfold microvasculature pattern, part of which was not directly seen with the capillaroscopy. OCTA imaging revealed significant changes in the nailfold microvasculature when a large external pressure was applied via arm compression, but no significant changes were observed using capillaroscopy. The capillary density measured by OCTA and capillaroscopy was 6.8±1.5 and 7.0±1.2 loops/mm, respectively, which was not significantly different (P=0.51). However, the capillary diameter measured by OCTA was significantly larger than that measured using capillaroscopy (19.1±2.5 vs. 13.3±2.3 µm, P<0.001). The capillary diameter measurements using OCTA and capillaroscopy were highly reproducible (ICC =0.926 and 0.973, respectively). While the capillary diameter measured with OCTA was significantly larger, it was rather consistent with the diameter measured using capillaroscopy (ICC =0.705). Conclusions: This study demonstrated that OCTA is a potentially viable and reproducible tool for the imaging and quantification of the capillaries in the nailfold microvasculature. The results of this study provide a solid basis for future applications of OCTA in qualitative and quantitative assessment of nailfold microcirculation in vivo.
RESUMEN
Two cyanide-bridged V-shaped isostructural trinuclear complexes [{(Tp*)FeIII(CN)3}2MII(bztpen)]·Sol (M = Fe, Sol = CH3OH·3H2O, 1; M = Co, Sol = 2CH3OH·2H2O, 2; bztpen = N-benzyl-N,N',N'-tris(2-methylpyridyl)ethylenediamine; Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) were synthesized and characterized. The bztpen ligand serves as a tetradentate capping ligand around the inner metal ion, leaving one pyridyl group intact. Complex 1 exhibits a spin crossover (SCO) behavior between the {FeIIILSFeIIHSFeIIILS} and {FeIIILSFeIILSFeIIILS} spin isomers, while 2 shows both thermally- and photo-induced electron-transfer coupled spin transition (ETCST) property between the {FeIIILSCoIIHSFeIIILS} and {FeIIILSCoIIILSFeIILS} valence isomers. The total entropy changes for 1 and 2 between their corresponding two electronic states were found to be very close with the values of 87.46 and 84.49 J mol-1 K-1, respectively, indicating the comparable thermal energy barriers necessary for either an SCO or ETCST event for such a given system. Furthermore, both complexes undergo desolvation-induced irreversible and sharp magnetic change at high temperatures.
RESUMEN
Three cyanide-bridged {Fe2Fe} complexes of formula {[(TpR)Fe(CN)3]2[Fe(bnbpen)]}·S (TpR = Tp for 1·S, Tp3-Me for 2·S, and Tp* for 3·S, respectively; bnbpen = N,N'-bis-(2-naphthylmethyl)-N,N'-bis(2-picolyl)-ethylenediamine) have been prepared and characterized here. Single-crystal X-ray diffraction analysis revealed that all compounds feature right angled trinuclear structures with two [(TpR)Fe(CN)3]- units at the ends and one [Fe(bnbpen)]2+ at the centre. Besides the rich hydrogen bonds, remarkable π-π interactions are evidenced in all compounds between the intermolecular naphthyl and pyrazolyl rings. As a result, compounds 1·S and 2·S exhibit irreversible two-step and one-step spin-transitions, respectively, during the process of removing solvents, with T1/2 at 314 K and 376 K for 1·S and 350 K for 2·S, while compound 3·S shows a reversible one-step spin transition at relatively lower temperatures with T1/2 = 250 K, and what's more, an irreversible small magnetic change accompanied by the loss of lattice solvents was observed. The solvent-free compounds show SCO properties at lower temperatures than the corresponding solvated ones; however, the solvent-free compound 1 maintains an unexpected high-spin state and does not follow the trend that their transition temperatures decrease with the enhancement of the electron donor properties of the TpR ligands (Tp* < Tp3-Me < Tp), likely due to the more compact π-π stacking mode in comparison with those for compounds 2·S and 3·S.